Investigators work at the scene where a train derailed at 47th Street and Archer Avenue in Chicago on Friday morning. The derailment delayed Metra trains on the Heritage Corridor line and blocked traffic in the area. (Keri Wiginton, Chicago Tribune)

(Keri Wiginton, Chicago Tribune)

Investigators work at the scene where a train derailed at 47th Street and Archer Avenue in Chicago on Friday morning. The derailment delayed Metra trains on the Heritage Corridor line and blocked traffic in the area.

Investigators work at the scene where a train derailed at 47th Street and Archer Avenue in Chicago on Friday morning. The derailment delayed Metra trains on the Heritage Corridor line and blocked traffic in the area. ((Keri Wiginton, Chicago Tribune))

Investigators work at the scene where a train derailed at 47th Street and Archer Avenue in Chicago on Friday morning. The derailment delayed Metra trains on the Heritage Corridor line and blocked traffic in the area.